Isolated Chapel (and some alpha testing)

Firstly, yes, the new homepage ( looks a little weird right now. Once the next crawl of prices is complete it will hopefully fix itself somewhat. In addition, we’ve noticed some major issues with the way we handle prices of old, high-value cards that are very thinly traded and we’re working on fixing those by tomorrow.

Next – given the new Sorin, Lord of Innistrad preview, people are eager to pick up black/white dual lands. For example, check out this reddit post:

Now, look at this graph of the number of “in stock” copies of Isolated Chapel at Starcity:


Notice the huge downswing? That implies these things are selling like hotcakes.

We haven’t noticed an upswing in prices yet, but we can see one around the corner if the buzz continues.

Mindbreak Trap – from $2 to $8?

We’ve been tweeting about Mindbreak_Trap for a couple of days now. The Ebay price has nearly doubled since Christmas, vendors have really spiky volumes (indicating lots of sales) and some vendors are significantly raising prices.

This is a mythic rare that came out 2 years ago, costs $2 and is a 4-of in many sideboards since it hoses combo, can counter uncounterable cards and is played for free against anyone who plays 3 spells.

Think it can hit $8 given the new modern format?

Implementing features is hard!

We’ve been quiet for a while now but we’d like to stress that this isn’t because we’ve stopped working – quite the opposite! Instead, we have been working on new features for out January 1st 2012 launch.

Today was the first day that we rolled out the new features to our closed beta users. (A “closed beta” is simply a beta test with a few hand-selected users who are happy to use a site full of bugs.)

This is a fairly significant milestone in terms of the site – our “core launch” features are actually live and running right now and it looks like we will be “feature complete” (that is, only working on bugfixes) by the 23rd of December. This is the day that we will open up our public beta to those users who signed up (link is on the front page).

The initial features are fairly simple – users are able to track their own collections along with trades and new additions and to see the price of their collections over time.

In addition, users can see how things like the 2011 World championships affected the price of single cards or their entire collection.

Additionally, users will be able to create decklists and share them with anyone interested, and again, these lists will show historical prices over time so you can see how different events impacted the price of various cards.

The decklists will show users who are logged in the cards they are mising and we have set up one-click ordering of only the cards that you still need to finish your deck at the lowest prices around.

We also allow users to log trades via the wizard that we released earlier (it now has a new look) – this will let you determine if you consistently make good trades over time and should let you keep your collection up to date more easily.

Lots of cleanup has also been added, including (finally!) access to foil card prices. We’ve always been gathering these prices, so you should have several months of data to peruse when the feature goes live on January 1st.

Alerts have also been added. These alerts are user-configurable and can be set up to tell you if any card is selling below a specific threshold price, a percentage below the “Fair Trade Price” or is significantly trending up or down. It’s also possible to view lists of cards sorted by recent gains and losses and those cards that are selling significantly below their typical price at a specific vendor.

The features above, while fun, are just the beginning – we’ll be rolling out at least one significant new feature every 2 weeks for the forseeable future. Our goal is, and always has been, to build a site with the fastest, most reliable MTG card prices around and to give players the tools to use this data effectively.

Look for more blog posts with further details and sign up for the beta if you haven’t already!

Finding a “Fair Trade Price” for a card

At our goal is to always show how much a “fair” price is for a given card. To do this, we gather prices from all over the Internet and show them, along with their history, on our card pages.

We noticed a serious outlier today with the “average” prices – several cards had been input incorrectly by a single store and this skewed the average price of all cards significantly. To avoid this occurring in the future, we’ve decided to implement a new version of Fair Trade Price beginning with updates tomorrow.

The new algorithm works as follows:

We aim to find prices of cards that have been sold recently. “Recently” is highly dependent on the card itself – Black Lotus typically change hands less frequently than a play-set of lightning bolts, for example. It’s important to get a value for how much a card sells for, not how much it is listed for. I can list 500 Lightning Bolt’s for $1000 each on Ebay but unless someone buys them, this price is irrelevant. Our algorithm therefore is essentially a weighted average of the current prices at various stores, weighted by the number of sales those stores typically have.

How do we know how many cards a given store sells? We don’t, not really, but we can guess based on the inventory levels that the stores publish. We’ve been collecting inventory information from all the big stores plus Ebay, amazon and all the stores for over a month now and we feel fairly confident in our initial ranking of weights.

We normalized the weights so that Ebay count’s as a multiplier of 1. Our first attempt at weighting sales is as follows:

Ebay x1

Starcity x0.84

ABUGames x0.64

MTGMintCard x0.22

TCGPlayer LOW x1.12

As we add in other stores and update our data, these weights will change. We will update all weightings on the 1st of every month to show how important each vendor is in our index.

How do these weights work? An example:

Liliana of the Veil is currently (11/20/2011 at noon) listed for:

Ebay - $35.62
Starcity - $39.99
ABUGames - $47.99
MtgMintCard - $52.99
TCGPlayer LOW - $32.13

The calculation that we do is as follows:

((35.62*1) +(39.99*0.84) + (47.99*0.64) + (52.99*0.22) + (32.13*1.12))/(1+0.84+0.64+0.22+1.12)

= $38.63 Fair Trade Value

This calculation will start being used on all cards starting tomorrow – we’re just running the final tests now to ensure we catch all the outliers and bad data before it comes into the calculation. Specifically, we throw away any single event that is more than 3 standard deviations away from the mean, unless there is more than 1 such occurrence. Later, we plan on using (stat’s geek alert!) Chauvenet’s criterion to detect outliers instead.

We want our prices to be the fastest and most accurate on the web. If you have any comments on how we plan to do things, or just want to say hello we can be contacted at or on Twitter or Facebook, or post in the comments section below.